RESUMEN
Hypereosinophilia is a rare presentation in all age groups, particularly when it is severe, persistent, and progressive. We describe the clinical characteristics and course of severe hypereosinophilia in a full-term Saudi female neonate. A febrile respiratory illness evolved with a progressive increase in peripheral blood leukocyte and eosinophil counts, reaching 44.9% of leukocytes and an absolute value of 57,000 cells/µl. Different etiological examinations (for viral, bacterial, immunodeficiency, hyper IgE syndrome, gene mutations) revealed extremely high CMV antigenemia and a homozygous mutation in the STAT1 gene. Anhelation was relieved by oxygen and anti-viral treatment. Steroids brought a dramatic response in peripheral blood counts within 24 h. After a 6-week course of antiviral and steroid treatment at home, she had an excellent general condition. Conclusion: Although a rare pathology, it is important to consider genetic disorders when there is an atypical immune response to viral infections.
